Apparatus for use in deviated wells

ABSTRACT

A WELL SCREEN IS DISPOSED ON A STRING OF PRODUCTION CONDUIT ON A LENGTH OF CONDUIT AT LEAST ONE END OF WHICH IS JOINED TO ADJACENT CONDUIT LENGTHS BY A BALL JOINT CONNECTION. THE BALL JOINT CONNECTION HAS A MAXIMUM OUTSIDE DIAMETER SIGNIFICANTLY SMALLER THAN THE DIAMETER OF THE BOREHOLE WALL, AND A MINIMUM INSIDE DIAMETER SUFFICIENT FOR MAINTAINING AN UNOBSTRUCTED CENTRAL PASSAGEWAY THROUGH THE CONNECTION. CENTRALIZER SPRINGS ARE POSITIONED AROUND THE BALL JOINT CONNECTION.

United States Patent [72] Inventors Fred W.Gerw1ck Lalayette. La.:

Harold C. Block. deceased. late of Houston. Tex.: Margaret D. Block. Exeeutrix,

Houston, Tex.

2: Appl. No 805,905

[22] Filed Mar. 10,1969

[45] Patented June 28, I971 [73] Assignee The Layne & Bowler Company Houston, Tex.

[54] APPARATlJS FOR USE IN DEVIATED WELLS 7 Claims, 4 Drawing Figs.

[52] U.S.Cl 166/278, 166/51, 166/227, 166/241 [51] 1 lut.Cl. 1521b 33/13, E031) 3/18 [50] Field otSearch 285/261,

[56] References Cited I UNITED STATES PATENTS 201,689 3/1878 Leermo 1,346,523 7/1920 Bard 1. 285/271 1,998,833 4/1935 Crowe11.... 166/241 2,167,194 6/1939 Anderson. 175/61 2,506,096 5/1950 Marshall 285/266 2,710,170 6/1955 Livingston... 175/61 2,829,864 4/1958 Knapp 175/61 Primary Examiner-James A. Leppink Attorneys-Arnold, White & Durkee, Tom Arnold, Donald C. Roylance, Walter Kruger, Bill Durkee, Frank S. Vaden, 111 and Louis T. Pirkey ABSTRACT: A well screen is disposed on a string of production conduit on a length of conduit at least one end of which is joined to adjacent conduit lengths by a ball joint connection. The ball joint connection has a maximum outside diameter significantly smaller than the diameter of the borehole wall, and a minimum inside diameter sufficient for maintaining an unobstructed central passageway through the connection. Centralizer springs are positioned around the ball joint connection.

APPARATUS FOR USE IN DEVIATED WELLS BACKGROUND OF THE INVENTION This invention relates to wells such as oil, gas, and water wells. More specifically, the invention relates to apparatus for use in wells wherein the borehole deviates from a substantially straight line.

Recently, operators of existing cased wells in relatively soft formations, particularly those wherein a large amount of sand is produced in the production fluids, have discovered kinks developing in the boreholes in many instances. Such deviation was generally detected after removal of the settings in the well, for workover and cleaning of the well, when it was attempted to run new settings into the well. At first it was thought that the casing had collapsed, but upon further investigation it was found that deviations had developed in the borehole and that kinking of the borehole had occurred. Specifically, deviations on the order of 7 8 have been detected within a distance of IO feet. It is believed that the production of large amounts of sand from an area adjacent the well, thus creating a voidin this area, has acted to suck the easing into the void area and thus cause the casing to kink.

It is quite common practice to utilize well screens in the type of formations discussed above, the use of such screens being discussed, for example, in U.S. Pat. No. 3,428,l28. Such screens are generally positioned adjacent the area from which sand is removed, hence the area wherein the kinking problem occurs. Since well screens are designed to restrict the passage of sand particles therethrough, thus controlling the sand production, it is readily seen that their utility is destroyed if on passage into the well, they are torn or physically damaged in any other manner which would open a channel into the screen thus allowing fluid to bypass the screen grid. The kinking problem discussed above is especially critical in this context, since it is readily seen that a well screen is quite vulnerable to damage upon being passed into a kinked borehole, by striking the restricted edges of the kinked casing or borehole and being forced through the restricted passageway.

The solution of this problem is difficult in that it must not create more problems than it solves. Chief among the problems created by some proposed solutions, is restricting of the fluid passageway through the production conduit of which the well screen and its associated tubing is a part.

The present invention provides apparatus for solving these problems, while leaving an unrestricted central passageway through the production conduit which is substantially as large as the mean inside diameter of the production tubing.

SUMMARY OF THE INVENTION In one embodiment, the present invention provides apparatus comprising a well screen on a production conduit in a well, the well screen being joined to adjacent lengths of the production conduit by at least one ball joint connection, the ball joint connection permitting rotation and flexing of the well screen with respect to the balance of the production conduit, while leaving an unobstructed central passageway through the connection which is substantially as large as the mean passageway through the production conduit.

In another embodiment, the invention provides such a ball joint connection of a size convenient for fitting into the well without danger of sticking the connection in the borehole, said connection comprising an outer casing, an inner member including a ball portion, and sealing means therebetween.

In yet another embodiment, the invention provides a centralizer spring arrangement on such a ball joint to assure centering of the ball joint in the borehole.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described with reference to certain preferred embodiments which are illustrated in the accompanying drawings which form a part of this specification and wherein:

FIG. 1 is a partial elevational view of a borehole having a production string therein, said production string including a well screen affixed to the production string in a typical prior FIG. 3 is a view similar to FIG. 2, but including apparatus in accordance with the present invention; and,

FIG. 4 is an exploded sectional view of a portion of the FIG. 3 apparatus. DETAILED DESCRIPTION OF THE ILLUS- TRATED EMBODIMENTS Certain embodiments of the invention are discussed here in detail, these embodiments constituting the best mode of the invention as of the date of this application.

Referring to FIG. I, there is shown a borehole 10 communicating from the earth's surface with at least one producing formation 12 through a nonproducing formation 14. A production conduit or string of tubing 16 is disposed in the borehole, the string communicating to the producing formation 12.

Disposed about a portion of the tubing string 16 in the area of production is a well screen 18, one type of well screen being described in Layne, U.S. Pat. No. 1,975,162. The screen 18 is designed to permit the flow of well fluids into the production conduit, while restricting the flow of sand particles into said production conduit. A well casing 36 contains perforations 38 adjacent the producing formation 12, and the well screen is located adjacent these perforations 38. It will be realized that well casing is not employed in every well; the present invention, however, finds its greatest utility in those wells employing well casing and wherein a portion of the casing is kinked or deviated from a straight line. In these specification and claims, the terms borehole" and casing" are sometimes used interchangeably and without regard to whether the hole is actually cased or not.

The tubing string 16 of this embodiment terminates in a rounded end portion 24, and desirably includes any suitable number of guide lugs 26, 28.

By way of one example, a void 32 is shown in FIG. 1, indicating the removal of sand from this area over a prolonged period of production.

The apparatus shown in FIG. 1 is illustrative of the prior art apparatus of this type.

FIG. 2 assumes that the casing has kinked into the void 32, resulting in a deviation or crooked portion 30 in the lower part of the borehole 10. As is seen in FIG. 2, the prior art apparatus cannot be passed into the kinked borehole, at least not without damaging the well screen 18.

The apparatus of the present invention is illustrated in FIG. 3, and in this drawing it is seen that the apparatus has been freely passed into the kinked borehole, in a manner such that the well screen 18 is adjacent the perforations 38 in the casing 36.

In accordance with the FIG. 3 embodiment, a couple of ball joint connections 20 and 22 are provided in the tubing string on either side of the well screen 18. These joints are such that the length of conduit on which the well screen is placed is free for angular flexing with respect to the portions of the conduit immediately adjacent the screen on both sides thereof. The ball joint connections also allow for rotation of this length of conduit with respect to its adjacent sections, and at the same time provide for an unobstructed central passageway through the center thereof. Also, the ball joint connections are of sufficiently small external diameter that they may convenientlyfrt through the borehole opening.

It will be recognized that in some contexts of use, a single ball joint connection of this type may be satisfactory, although connections both above and below the screen will usually be desirable. Also, it will be recognized that, especially for use in plural production zones where the deviation problem may occur in more than one zone, any number of screens might be included between like ball joint connections. Further, it may be satisfactory in some instances to use more than onesection The connection comprises generally an outer casing 40, 1

an elongate inner member 50, and sealing means therebetween.

Outer casing 40 includes a first generally tubular portion 42 at one end thereof (the upper end in the FIG. 4 embodiment), the inner surface of portion 42 having a diameter d and being internally threaded for mating threaded engagement with an adjacent length of productionconduitl6. The outer surface 43 of portion 42 presents a generally smooth surface and has a diameter d, which is approximately equal to the mean outside diameter of the production conduit 16. By mean" (outside or inside) diameter of the production conduit is meant that diameter most frequently'occurring in the production conduit.

production conduit has an outside diameter of 2% and an inside diameter of 1 15/16 inches 5 inches,-then the mean outside and inside diameters of production conduit 16 are 2% and l l5/l6, respectively.

Joined to the first portion 42 through an outwardly tapered neck portion 44, is a's'econd generally tubular or'collar portion 46 of outer casing 40. The outside surface 47 of collar 46 has a diameter d, which is significantly greater than the mean outside diameter of the production conduit 16, and may represent the largest diameter of any portion of the production conduit. The inner surface of collar 46 includes a nonthreaded portion 49, and at its end opposite the first portion 42, a threaded portion 48. The threaded portion 48 and nonthreaded portion 49 define the outer edge of a relatively large interior chamber 51 into which a ball is adapted to fit. The size of chamber 51 is such .that a ball may occupy the chamber and still leave an unobstructed central passageway.

in cross section, theend of nonthreaded portion 49 nearest the neck 44 is seen to present a square corner into which a '40 sealing gasket may be fitted.

The elongate inner member of ball joint 20 includes a ball portion 52 and a collar 56, joined by a stem 54.

The ball portion 52 is disposed at one end of the member 50 and is adapted for fitting into the chamber 51. The exterior surface 53-of ballportion 52- is spherical in shape, although it is recognized that the ball 52 forms only a segment of a sphere rather than a complete sphere. I

The inner surface 57 of collar 56 of member 50 is threaded for matingeng'agement with an adjacent length 34 of production conduit, and the outer surface 59 of collar 56 is generally smooth. The well screen 18 is disposed on the length 34,'and the screen 18 may be considered to form a portion of the production conduit.

The inner surface of stem 54 which connects ball 52 and collar 56, has a diameter d, which is substantially equal to the mean inside diameter d, of the production conduit '16. The surface 55, along with the inner surface 58 of ball portion 52, forms a part of the wall defining the conduit through well fluids are produced.

Suitable sealing means are employed between the outer casing 40 and inner member 50 of ball joint 20. Such means desirably include a gasket 70, advantageously formed of asbestos material, which gasket fits into the square corner 45 and has an inner surface 72'which seals against the spherical outer surface 53 of ball portion 52. Y

Additionally, the sealing means may include a metal sleeve 60, a portion of the exterior surface 62 of which is threaded to mate with the threaded portion 48 of collar 46 of'outer casing 40. From each end of the sleeve 60, surfaces 64 and 66 are inwardly tapered to join with a spherical surface 68 which is adapted to form a metal-to-metal seal with the outer surface 53 of ball portion 52. I While the term sealing means" is used in this specification and claims, it will be understood that an absolutely perfect seal is not mandatory since the well screen itself admits fluid into the production conduit. Consequently, it will be seen that the exact nature of the sealing means employed is not critical to the invention. 1

g In dotted lines in FIG. 4, an unobstructed central passageway 74 is indicated through the ball joint 20.

The degree of angular flexing permitted by the ball joint 20 is indicated by the arcuate distance d,, in this embodiment 15 on-each side of the longitudinal axis 76.,

In many contexts of use, itis desirable to include means to insure centralizing of the ball' joint 20 with respect to the borehole wall. Such means may desirably include a plurality of resilient springs such as 7 8 and 80. 1

Although two springs are .shown in this embodiment, any suitable number may be employed. Since the springs 78 and 80 are similar in construction, only spring 80 will be described in detail. 1 v

The spring 80 includes ast'raight base portion 82, an outwardly bowed intermediate portion 83, and a free end portion The base portion 82 of spring 80 is attached as by welding to a ring 90, which is, in turn, affixed to the outer surface 59 of collar 56.

An inner portion 86 adjacent free end 84, is free for limited movement against the outer surface-43 of collar portion 42. An outer surface 88 of intermediate portion 83 of the spring 80 is of maximum diameter and is therefore adapted for first contact with the wall of the borehole. The resiliency of spring 80 is such that, when the surface 88 contacts the borehole (or casing) wall, the portion 86 rides'up along the surface 43. Relative differences in the flexing of springs 78 and 80 combine to bias the ball joint 20 towarda central position in the borehole.

It is seen that the ballv joint 20-permits free rotation, and limited flexing, of the inner member 50 and its associated lengths of production conduit, with respect to the outer casing 40 and its associated lengths of production conduit, while leaving an unobstructed central channel through the apparatus.

It is seen from the above discussion that the invention accomplishes the objects and attains the advantages listed above, and solves'the problems outlined at the beginning of this specification.

vlt will be understood by those of skill in the art that various changes in the specific structures of the illustrative embodiments may be indulged without departing from the scope of the invention which is defined in the appended claims.

We claim:

1. In a string of tubing suitable for positioning in a borehole to provide communication between the earth's surface and a producing formation, the improvement comprising:

a ball joint connection joining at least one length of tubing providing a well screen to the tubing string, said ball joint including: H an outer casing which has a portion of greater diameter than the mean outside diameter-of said tubing string, and a portion of smaller outside diameter at the end of said casing opposite said greater diameter portion, and an inner member including a ball portion for fitting within said greater diameter portion, and a collar portion at its end opposite said ball portion, said collar portion being positioned in a direction away from aid smaller diameter portion of said outer casing, at least one centralizer spring,

one end of said spring being fixed adjacent the exterior surface of said collar portion,

an intermediate portion of said spring being outwardly bowed for first contact with the wall of said borehole, and the other end of said spring being free for limited movement upon contact of the intermediate portion of said spring with said borehole wall, but said free end being normally positioned adjacent the exterior surfaceof said smaller diameter portion of said outer casing.

2. in a string of tubing suitable for positioning in a cased borehole to provide communication from the earth's surface to a producing formation, the improvement comprising:

at least one length of tubing adapted for fitting into said tubing string where casing is deviated;

a well screen around said length of tubing;

a ball joint connection at at least one end of said length of tubing, connecting said length into said tubing string, said connection permitting substantially free rotation of said length with respect to said tubing string, and at least slight angular flexing of said length with respect to the portion of said tubing string immediately adjacent said length; and

said length of tubing, well screen, and ball joint connections being constructed in a manner such that an unobstructed central passageway substantially as large in diameter as the mean inside diameter of said tubing string, is provided through said length and said connections.

3. Apparatus in accordance with claim.2, wherein said ball joint connections are provided at both ends of said length of tubing.

4. Apparatus in accordance with claim 3, wherein said length of tubing is capable of angular flexing of at least with respect to immediately adjacent lengths of tubing above and below said length.

5. Apparatus for use in gravel packing a well having a deviated casing comprising:

an elongated well screen for connection to the lower end of a tubing string to be lowered into a cased well, the casing being angularly deviated in the vicinity of a producing formation;

a ball joint connection at at least one end of said well screen, connecting said well screen into said-tubing string, said connection permitting substantially free rotation of said well-screen with respect to said tubing string, and at least some angular flexing of said well screen with respect to the portion of said tubing string immediately adjacent said well screen; and

said well screen and ball joint connection being constructed in a manner such that an unobstructed central passageway substantially as large in diameter as the mean inside diameter of said tubing string, is provided through said connection.

6. Apparatus according to claim 5 wherein centralizer springs are disposed around said ball joint connection in order to bias said connection toward the center of the well.

7. A method of reworking a cased well of the gravel packed type wherein angular deviations occur in the vicinity of producing formations, comprising the steps of:

withdrawing the existing tubing string;

connecting a section of tubing a well screen therein to the lower portion of a tubing string, with a ball joint connection between the tubing string and the well screen, running in the tubing string with well screen attached whereby the well screen enters the deviated portion of the casing in the vicinity of the producing formation, the axis of the well screen turning substantially with respect to that of the tubing string as permitted by the ball joint connection; and

thereafter gravel packing the well in the vicinity of the well screen. 

